The present invention relates to a color copying system. More particularly, this invention concerns an electrostatic color-copying apparatus.
An electrostatic color copier normally breaks down the image to be copied into several color-component beams, usually each corresponding roughly to one of the primary colors. To this end the image must be scanned several times, usually with the beam being passed through a filter and being produced by illumination of the surface being scanned with light of colors that suppress all but the desired color. The beams are then reflected onto a large image surface and an image former or toner of the requisite color is applied thereto for each beam. The separate images must register perfectly. The different toners can then be jointly transferred to a copy sheet and fixed so that the combined toners produce a copy image corresponding closely to the original on the master.
IT IS ABSOLUTELY ESSENTIAL IN SUCH SYSTEMS THAT THE IMAGES FORMED FOR EACH COLOR COMPONENT REGISTER PERFECTLY. For this reason recourse has usually been had to a planar image-receiving surface.
In order to increase the precision of registration it has been suggested to scan for all of the color components simulataneously through slit shutters spaced apart in the direction of scanning so that the variously colored image formers are laid on the image surface one behind the other and the chance of misregistration is greatly reduced.
Almost invariably such systems have complicated lens and reflecting arrangements that greatly increase the cost of the machine and the cost of the copies made thereby. Furthermore, these systems can only be employed with a planar image-receiving surface whose use greatly increases the size of the machine and the difficulty of transferring the image to a copy sheet without blurring.